It is known that an optically active (E)-7-[2-cyclopropyl-4-(4-fluorophenyl) quinolin-3-yl]-5-hydroxy-3-oxohept-6-enoic acid ester (hereinafter referred to as compound (III)) of formula (III)
wherein R is an alkyl having 1 to 4 carbon atoms which is a desired compound of the present invention, is produced by reacting (E)-3-[2-cyclopropyl-4-(4-fluorophenyl)-quinolin-3-yl]-prop-2-en-1-al (hereinafter referred to as compound (II)) of formula (II)
with diketene in an organic solvent in the presence of an optically active Schiff base-titanium complex prepared by reacting an optically active Schiff base with a titanium compound (Japanese Patent Laid-open No. Hei 8-92217).
In addition, Tetrahedron Asymmetry, Vol. 11, 2255–2258 (2000) and Tetrahedron Asymmetry, Vol. 12, 959–963 (2001) describe processes for producing an optically active alcohol by reacting 1,3-bis(trimethylsilyloxy)-1-alkoxybuta-1,3-diene (hereinafter referred to as compound (I)) of formula (I)
wherein R is an alkyl having 1 to 4 carbon atoms, with an aldehyde in the presence of an optically active binaphthol-titanium complex.
However, the process disclosed in Japanese Patent Laid-open No. Hei 8-92217 is troublesome as it requires a plurality of steps for preparing the optically active Schiff base-titanium complex. Further, the optical purity of compound (III) produced by the process is about 78% ee, therefore a further optical resolution is required for obtaining compound (III) having such a high optical purity that it can be used as an intermediate for synthesis.
In addition, the process disclosed in Tetrahedron Asymmetry, Vol. 11, 2255–2258 (2000) and Tetrahedron Asymmetry, Vol. 12, 959–963 (2001) give desired compounds in a relatively high yield and optical purity, but it requires not only strict reaction conditions, such as distillation and purification of a solvent to be used but also an addition of a molecular sieve dried at a high temperature during the preparation of the complex. Thus, it is hard to regard the process as a practical one.